Cask handling system and method

ABSTRACT

A system and method for removing spent fuel assemblies from a fuel building and transporting them to on-site facilities. A cask transporter is moved into the fuel building with an empty spent fuel storage cask, spent fuel assemblies are loaded into spent fuel storage cask, the cask is sealed, and the cask transporter moves the loaded spent fuel storage cask to a handling area for final disposal. Components of the system include a penetration cover, a lifting mechanism, a control system, a valve system, and the cask transporter.

RELATED APPLICATIONS

This Application is a continuation of U.S. patent application Ser. No.13/497,737 filed on Nov. 5, 2012, now U.S. Pat. No. 9,824,781, which isa national phase application of International Application NumberPCT/US2010/50397 filed on Sep. 27, 2010, which claims the prioritybenefit of U.S. provisional Patent Application No. 61/245,881 filed onSep. 25, 2009, the disclosures of which is expressly incorporated hereinin its entirety by reference.

FIELD OF THE INVENTION

The present invention generally relates to systems and methods forhandling massive containers and, more particularly, handling storagecasks for nuclear waste material.

BACKGROUND OF THE INVENTION

Nuclear power plants are required to have systems and methods forremoving spent nuclear fuel from the plants so that it can be storedand/or processed. The spent nuclear fuel is typically stored in casks.While the current systems and methods may handle the casks, they have anumber of problems. Existing systems have little documentation, requiresignificant man hours, and use out-dated technology. These currentmethods also require a relatively large number of single use componentsthat makes these systems expensive and difficult to maintain.Accordingly, there is a need in the art for improved systems and methodsfor handling casks containing nuclear waste material.

SUMMARY OF THE INVENTION

The present invention provides a system and method that overcomes atleast some of the issues of the related art. Disclosed is a method forremoving spent nuclear fuel comprising the steps of moving a cask belowa penetration using a transporter, raising the cask from the transporterusing a handling mechanism engaging only upper trunnions of the cask sothat the cask self-aligns with the penetration using gravity, securingthe cask to the penetration, inserting the spent fuel into the cask,unsecuring the cask from the penetration, and lowering the cask onto thetransporter using the handling mechanism.

Also disclosed is an upper handling mechanism for handling a sentnuclear fuel cask having pairs of upper and lower trunnions. Themechanism comprises, in combination, a fixed position frame, a toolmovable in the vertical direction relative to the frame, a plurality ofhydraulic cylinders for vertically moving the tool relative to theframe, and a pair of paddles pivotably attached to the tool forselectively engaging the upper trunnions of the cask.

Also disclosed is a method for removing spent nuclear fuel comprisingthe steps of moving a cask below an opening at a first station using aself-powered transporter, rotating the cask from a horizontalorientation to a vertical orientation at the first station, moving thecask below hoist at a second station using the self-powered transporter,moving the cask below a penetration at a second station using theself-powered transporter, raising the cask from the self-poweredtransporter to the penetration, securing the cask to the penetration,inserting the spent fuel into the cask, unsecuring the cask from thepenetration, and lowering the cask onto the self-powered transporter.

Further disclosed is a self-powered vehicle for transporting a spentnuclear fuel cask having pairs of upper and lower trunnions. The vehiclecomprises, in combination, a body, an upender secured to the body forholding the cask and moving the cask between vertical and horizontalorientations, and a plurality of independently driven and independentlysteered wheels on each lateral side of the body.

From the foregoing disclosure and the following more detaileddescription of various preferred embodiments it will be apparent tothose skilled in the art that the present invention provides asignificant advance in the technology of systems and methods for spentnuclear fuel removal. Particularly significant in this regard is thepotential the invention affords for providing an, reliable and effectivesystem and method for handling spent nuclear fuel casks. Additionalfeatures and advantages of various preferred embodiments will be betterunderstood in view of the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further features of the present invention will be apparentwith reference to the following description and drawings, wherein:

FIG. 1 is a perspective view of fuel building or facility having a casttransfer system according to the present invention.

FIG. 2 is a plan view of the cask transfer assembly of FIG. 1.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2.

FIG. 3A is an enlarged, fragment view showing a portion of FIG. 3.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2.

FIG. 4A is an enlarged, fragment view showing a portion of FIG. 4.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is a perspective view of a cask transporter of the cask handlingsystem of FIGS. 1 to 5, wherein the cask is held in a horizontalorientation.

FIG. 7 is a perspective view of the cask transporter of FIG. 6, whereinthe cask is held in a vertical orientation.

FIG. 8 is a perspective view of the cask transporter of FIGS. 6 and 7,wherein an upender is in a horizontal orientation without holding acask.

FIG. 9 is perspective view of a tire propulsion/support system of thecask transporter of FIGS. 6 to 8.

FIG. 10 is a perspective view of a rotary actuator of the tirepropulsion/support system of FIG. 9.

FIG. 11 is a perspective view of a hydraulic motor of the tirepropulsion/support system of FIG. 9.

FIG. 12 is a perspective view of a tire assembly of the tirepropulsion/support system of FIG. 9.

FIGS. 13A to 13D are bottom plan views of the cask transporter of FIGS.6 to 8, wherein different turning conditions are illustrated.

FIG. 14 is a perspective view of a diesel powered generator set of thecask transporter of FIGS. 6 to 8.

FIG. 15 is a perspective view of a safety catcher of a hydraulic liftsystem of the cask transporter of FIGS. 6 to 8.

FIG. 16 is a perspective view of an upper cask handling station of thecask handling system of FIGS. 1 to 5.

FIG. 17 is a perspective view of a lower seismic restraint of the caskhandling system of FIGS. 1 to 5.

FIG. 18 is a perspective view of a penetration upper hatch of the caskhandling system of FIGS. 1 to 5, wherein a hatch cover is closed.

FIG. 19 is a perspective view of a penetration upper hatch of FIG. 18,wherein the hatch cover is partially open.

FIG. 20 is an enlarged fragmented view of a portion of the penetrationupper hatch of FIGS. 18 and 19.

FIG. 21 is a schematic view of piping in a cask handling room of thecask handling system of FIGS. 1 to 5.

FIG. 22 is an electrical schematic view of a control system of the caskhandling system of FIGS. 1 to 5.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the cask handling system asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes will be determined in part by theparticular intended application and use environment. Certain features ofthe illustrated embodiments have been enlarged or distorted relative toothers to facilitate visualization and clear understanding. Inparticular, thin features may be thickened, for example, for clarity orillustration. All references to direction and position, unless otherwiseindicated, refer to the orientation of the cask handling systemillustrated in the drawings. In general, up or upward refers to anupward direction within the plane of the paper in FIG. 3 and down ordownward refers to a downward direction within the plane of the paper inFIG. 3.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

It will be apparent to those skilled in the art, that is, to those whohave knowledge or experience in this area of technology, that many usesand design variations are possible for the improved systems and methodsdisclosed herein. The following detailed discussion of variousalternative and preferred embodiments will illustrate the generalprinciples of the invention with reference to preferred embodiments.Other embodiments suitable for other applications will be apparent tothose skilled in the art given the benefit of this disclosure.

Referring now to the drawings, FIGS. 1 to 5 illustrate a fuel building10 having a fuel transfer or cask handling system according to thepresent invention 12. The illustrated cask handling system 12 handles aspent fuel storage cask 14 through the process of removing spent nuclearfuel from the fuel building 10 including providing an unloaded cask 14,preparing and opening the cask 14, loading spent fuel into the cask 14,sealing the cask 14, and removing the loaded cask 14 from the fuelbuilding 10. The cask handling system 12 includes a self-powered mobilecask handling vehicle or cask transporter 16, an upper handlingmechanism 18, a penetration cover 20, a seismic restraint 22, and avalve system 24.

A preferred method according to the present invention for removing spentfuel assemblies from a fuel building 10 and transporting them to on-sitefacilities for the next stage of disposal is as follows. First, acomplete empty cask 14 is placed onto the cask transporter 16 in thehorizontal or vertical orientation by an overhead gantry crane. The cask14 is securely attached to an upender structure 26 of the casktransporter 16 which can pivot the cask 14 about a horizontal andlaterally extending pivot axis 28 so that the cask 14 can be movedbetween horizontal and vertical positions. Precise positioning of thecask 14 onto the cask transporter 16 is not necessary because locatingthe cask 14 with respect to a fuel pool 30 and penetration 32 in thebuilding 10 is accomplished by the other equipment as describedhereinafter. With the cask 14 positioned in its horizontal position, thecask transporter 16 drives to the fuel building 10. The cask transporter16 has the ability to drive anywhere on site and can be operated by anon-board driver or by radio remote control. The cask transporter 16 hasa hydraulic power system that is powered by a self-contained motor andgenerator 36 (no external tractor or tugger is required). When insidethe cask transfer facility 10, the cask transporter 16 has the abilityto run on remote power via an umbilical cord. The cask transporter 16enters a cask loading hall or fuel hall 34 of the fuel building 10 andaligns itself with a pair of parallel, embedded floor rails 40. When thecask transport 16 is aligned with the imbedded floor rails 40 andcompletely with the cask loading hall 34, isolation doors are shut andtemporary power is connected to the cask transporter 16 via theumbilical cord. Because the cask transporter 16 is aligned with therails 40, side-to-side or lateral positioning of the cask transporter 16is automatically accomplished and precise positioning from front to backin a linear direction within the cask loading hall 34 can be obtained.

The upender 26 on the cask transporter 16 repositions the cask from itstraveling horizontal position to its vertical position, engages upperseismic constraints, and positions the cask 14 under a first processingstation which is the cask prep station 42. At the first station 42, ashock absorbing cover, protection lid, and fixing flange of the cask 14are each manually removed using an auxiliary crane located in the fuelbuilding 10. Personnel are located above the fuel hall 34 and access thecask 14 through a hole 44 in the floor. This provides a controlled andsafe work area for removing the covers and lids from the cask 14. Thecask components are stored on sliding shelves located adjacent the hole44. Once bolts for the biological lid of the cask 14 have been removed,the cask transporter 16 is moved by radio control to the second stationwhich is the biological lid station 46.

At the second station 46, a hoist 48 with a grapple device is manuallyoperated, aided with cameras, to maneuver the grapple to engage andremove the biological lid of the cask 14. With the biological lid movedout of the way, a thorough visual inspection of all seals and sealingsurfaces of the cask 14 is conducted by an operator using cameras.Redundant piping and hosing is connected into ports of the cask 14 atthis time. The cask transporter 16 is then moved by radio control to thethird station which is the cask loading station 50.

At the third station 50, the cask transporter 16 locates the cask 14under the penetration 32 of the fuel pool 30 and personnel disconnectthe cask 14 from the cask transporter 16. In this position, the cask islocated under the upper handling mechanism 18.

Hydraulically powered paddles 52 of the upper handling mechanism 18 havekey slots 54 which are extended and slide over upper trunnions 56 of thecask 14 to lock the cask 14 to the upper handling mechanism 18. With thecask 14 securely held by the paddles 52, the cask transporter 16 isbacked away and a vertical guide system or seismic restraint 22 risesfrom the floor and engages lower trunnions 58 of the cask 14. As thecask 14 is raised by the upper handling mechanism 18 from the casktransporter 16, the lower trunnions 58 engage a keyed structure 60 inthe vertical guide system 22, preventing a swinging pendulum motion in aseismic event. The cask 14 is lifted up by the upper handling mechanism18 and proper alignment of mating surfaces is visually verified usingcameras. A multi-stage redundant bladder system engages an inner face ofthe cask opening. Mechanical locking means engage and the paddles 52locate the cask 14 in alignment (similar to a plumb bob) using gravity.The redundant bladder system is then inflated to secure the seal. Aftersuccessful docking of the cask 14, the penetration 32 is filled withborated or de-mineralized water. Using vent and drain valves, the cask14 is filled with water and pressure is equalized on the two sides ofthe penetration upper cover 20. At this time, all personnel are exitedfrom the loading hall 34.

The penetration upper cover 20 is opened and remains opened andmonitored by cameras as spent fuel is loaded into the cask 14. As thecask has been loaded with spent fuel and the cameras verify that thespent fuel bundles are located properly, the penetration upper cover 20is closed. The area below the penetration upper cover 20 is drained,rinsed with de-mineralized water and allowed to dry. The water in thecask is lowered to the necessary level for the biological lid. The casktransporter 16 is then moved back to the cask loading station, thebladder seals are depressurized and the cask 16 is lowered from the sealand onto the cask transporter 16. The paddles 52 retract from the cask14 and mechanical means secure the cask to the cask transporter 16. Thecask transporter 16 then moves the cask 14 back to the biological lidstation 46 where the biological lid is placed back onto the cask 14 andthe remaining cask restraints are secured. Personnel are then allowedback into the loading hall 34.

Redundant piping and hosing is disconnected from the cask ports and allports are properly sealed. The cask transporter 16 then moves the cask14 back to the cask prep station 42. Remaining cask components arereassembled and properly engaged on the cask 14. Remaining caskconstraints are secured and the cask 14 is down ended to its horizontalorientation. Radiological tests are performed and decontamination isperformed as necessary. The doors in the loading hall 34 are opened andtemporary power to the cask transporter is removed, that is, theumbilical cord is removed. The cask transporter 16 then drives out ofthe fuel building 10 under its own power. The cask transporter 16 takesthe cask 14 to a handling area for final disposal.

As best shown in FIGS. 6 to 8, the illustrated cask transporter 16 is adiesel/electric, self-propelled, wheeled vehicle that transports thestorage cask 14 which weighs 125 tons. The illustrated cask transporter16 includes sixteen wheels 62 which are driven by industrial hydraulicmotors 64 with integral brakes for total control and greaterflexibility. The illustrated cask transport 16 has four pairs of wheels62 on each lateral side of the cask transporter 16. A diesel poweredelectric generator 36 provides power to operate the cask transporter 16.The cask transporter 16 preferably is designed to safely hold a TN32cask 14 during a seismic event. A dynamic multiplier of 1.15 ispreferably considered for impact loading during normal operations.Hydraulic fluids are preferably suitable for outdoor operation at 0degree Fahrenheit and are preferably non-flammable with a flashpoint> or=100 degrees Fahrenheit. High pressure hydraulic lines are preferablysecured and protected to prevent whipping in the unlikely event offailure. Hydraulic systems preferably carry the rated load, including a15% hoist factor. Calculated safety margins for cylinder buckling andhoop stress are preferably a minimum of 2:1 versus the buckling loadlimit and the material yield strength respectively. The cask transporter16 is sized and shaped so that it is stable to ensure that an upset willnot occur during normal or off normal events.

The illustrated cask transporter 16 can shuttle loaded and unloadedstorage casks 14 between the fuel handling hall 34 and any otheraccessible location at the site. The illustrated cask transporter 16 hasa unique turning mechanism and wheel design allows significantly moremaneuverability over prior systems. The cask transporter 16 preferablyincludes the following features: twenty year design life; all weatherdesign; OSHA compliant design; auto-rotating, fully loaded on concreteor other hard surface; key start switch; switch type speed control;diesel fuel tank of about forty to fifty gallons; heaters (sump pump,fuel tank, and hydraulic reservoir); dead man controls (brakes appliedupon release of control, loss of fluid pressure, or loss of power);traverse speed of 0.4 mph+/−0.05 mph on level ground; manual loweringcapability without power; warning lights and audible alarm (30 footrange); provisions to prevent uncontrolled lowering; portable fireextinguisher; float battery charger; access ladders and fall protection;control panel capacity nameplate (rated load, empty weight, temperaturelimitations); ability to traverse two inch lip of obstructions at thesite; durable outdoor paint system; and non-slip walkway surfaces.

The illustrated cask transporter 16 includes a body 66 which is the mainweldment vehicle frame. The body 66 is the center structure that tiesthe entire machine together. It is constructed from welded plates andstructural shapes. The body 66 serves as the mounting point for allother systems of the cask transporter 16 and also serves to support thecask 14. The body 66 is preferably a weldment constructed primarily frommild steel and structural shapes (ASTM A572 and A500C with yieldstrengths of 50,000 psi and welded per AWS D1.1). Welding complies withAWS D1.1. The structure is evaluated for both static and seismic loadrequirements.

As best shown in FIGS. 9 to 13, rubber tire propulsion/support systemsof the illustrated cask transporter 16 include the wheels 62, rotationmechanisms 68, and hydraulic drive units 70. The illustrated eight pairsof dual-rubber wheels 62 (four pairs on each side and sixteen totalwheels) are mounted on the underside of the body 66. The wheels 62 arepreferably foam-filled aircraft tires such as those available fromMichelin or equivalents that are designed for high capacities and highspeeds. Because the cask transporter 16 is traveling at very low speeds,these wheels 62 are conservatively designed for this function. Thefoam-filled tires ensure that there is never a flat tire that couldchallenge the safety of the fuel assembly with a transported cask 14.Each dual tire set is driven by the hydraulic motor 64. Based on a dirtsurface, a rotational speed of 3.056 rpm and 5% grade, each hydraulicmotor 64 is approximately 5HP and is independently controlled by thePLC. Each dual wheel set is independently steered using commerciallyavailable rotary actuators 72. The rotary actuators 72 are used to pivota joint where a conventional mounting proves impractical due to space,weight, or motion restrictions. These rack and pinion actuators 72provide high torque output, zero leakage drift-free positioning, andexcellent shock load resistance. These types of wheel sets are highlyreliable. A control system provides the signals to drive, turn androtate the wheels 62. Using a PLC that independently controls each ofthe dual wheel assemblies, the cask transporter 16 can turn as neededand drive around the entire site. The steering system provides theoperator with the capacity to rotate the cask transporter 16 on itself,that is pivoting about its center (best shown in 13D).

As best shown in FIG. 14, the illustrated cask transporter 16 includesthe diesel powered generator 36 located at the rear of the body 66 toprovide electrical power. The generator 16 includes a diesel engine,generator, diesel fuel tank, and all of the equipment to support theoperation of the engine and generator and are all contained within aframe of a module 74. The engine and generator are sized to manage themost demanding function as limited by the control system. The dieselengine drives the generator, which is selected to provide460V/3-phase/60 Hertz power to the cask transporter. This electricitypowers and electric motor/hydraulic pump module for the lift function ofthe upender 26 and either another electric motor/hydraulic pump modulefor the propel function of the wheels 62 or two electric propel motors.Noise suppression systems are included with the system to reduce the dbalevels workers are exposed to below OSHA limits. Operation of the casktransporter 16 requires that each function (propulsion, upending, etc.)be operated separately to maximize safety.

As best shown in FIG. 15, the illustrated cask transporter 16 employsautomatic drop protection to prevent uncontrolled lowering of the cask14 during any system failure, such as loss of pressure to the cylindersor other catastrophic failure of the lifting system 26. The casktransporter 16 preferably is equipped with a separate safety system.This safety system holds the cask 14 in a safe condition in the unlikelyevent that a hydraulic cylinder fails or other structural parts of thelifting system 26 fail to function. Separately mounted from thehydraulic cylinder, the safety system employs two commercially availableSITEMA safety catchers 76. Conventional locking devices fitted to thehydraulic presses (such as locking bolts or latches) often operate atthe top, or a few more positions. Form fitting systems have a gap insafety between where power is disrupted and the hole slide hits alocking point. These obvious disadvantages are avoided by using SITEMAsafety catchers 76. These safety catchers 76 prevent the cask 14 fromcrashing down at any stage of ascent or descent, are mechanically safeand reliable, and do not have a ratchet. A high safety standard, alongwith improvements in productivity, is achieved through: the load issupported on a holding shaft separate from the cylinder; the SITEMAsafety catcher clamps without a ratchet, so that a safe clampingcondition is attained throughout the entire stroke and a productivelyincrease is offered as the actual stroke can be limited to the lengththat is absolutely necessary; the clamping system is held open byhydraulic or pneumatic means so that when pressure drops, the cask 14 isimmediately secured; the energy of a falling or sinking load is used togenerate the clamping force which only happens if the load starts tomove downward from the secured position (when the safety catcher iswithout pressure). In this case, the cask 14 is securely stopped almostinstantly with help of the self-intensifying clamp movement; and SITEMAbraking operations are fully operational at all cylinder speeds andusually a deceleration of 1 to 3 g (acceleration due to gravity) isachieved and the resulting braking distance is not more than a fewcentimeters.

The illustrated cask transport 16 includes operator control system 78including control panels and a generator module console. The operatorcontrol system is ergonomically mounted on the top deck 18 of the casktransporter 16 to provide user friendly operation from a swivelingoperator's chair 82, in a location providing an unobstructed view ofcask handling operations. Next to the operator's chair 82 is astationary control console that has auxiliary indications. Theoperator's chair 82 can rotate approximately 270 degrees andautomatically reverses the joy stick controls based on the orientationof the chair 82. The operator's control is provided with a protectivecover to prevent weather damage. Hydraulics are operated by manipulationof solenoid valves that port fluid to extend and retract fromcommercially available hydraulic cylinders, such as those available fromParker. Counter-balance and pressure compensated flow valves ensure thatthe hydraulic system only operates when commanded, and is fail safe onthe loss of pressure from leaks or pump failure. Operating pressure willbe displayed on the stationary console plus additional warning lightsfor low hydraulic level and other fault conditions. The speed of thecask transporter 16 is controlled by a joy stick that is located on theoperator's chair 82. Based on the position of the joystick, a 0-10 VDCsignal is sent to a proportional valve that drives the eight hydraulicmotors 64 either in forward or reverse. The joystick is spring-returnedto neutral (0 position) to act as a dead-man switch. Steering iscontrolled by a multi-axis joystick that feeds a proportional signalthough a PLC, such as those available from Allen Bradley, or equivalentthat separately steers the eight pairs of wheels 62. The PLC programindividually controls the wheels 62 so that they are rotated correctlybased on their position on the cask transporter 16. Hydraulic fluiddrives the eight rotary actuators 72, such as Parker HTR serieshydraulic rotary actuators, with electronic feedback to properlyposition the wheels 62. A separate 75 HP motor drives a 28 gallon pistonpump that is connected to a 80 gallon HPU reservoir for steering andpropulsion. The tank comes with heat exchanger and heaters toaccommodate any environmental extreme. Strainers and filters arepreferably provided.

Controls for the cask transporter 16 are designed to be fail-safe, sothat loss of power will shut down the system and prevent an uncontrolledmovement of the cask 14. All safety interlocks and controls of the casktransporter 16 are hard wired between the specific relays, drives,circuit breakers, and other electrical equipment. The control system isdesigned per NEC standards and mounted within a minimum of NEMA 4enclosures. Wiring is mounted in rigid conduit except for necessaryflexible connections and at the interface between the conduit and theequipment. The cask transporter 16 is also grounded for personnel andequipment protection.

The upender 26 is powered by dual hydraulic brake-motors coupled top aplanetary gear set to drive a pinion/bull gear ensemble. Encoders areintegrated into each drive and set up as a master/slave configuration toensure the upending is done in unison. Rotation is about a pointapproximately within three inches or about 80 centimeters of the centerof gravity, therefore necessary power is kept to a minimum. In case offailure of one drive system, the other brake motor can hold the cask 14by itself and can be driven to lower the cask 14 back down to a safeposition. In addition, the fuel building crane can also be used to lowerthe cask 14 in case of a catastrophic failure. To prevent shock to thefuel assembly and cask 14, shock absorbers have been incorporated intothe bed for safety. The upender 26 can be extended approximately fortyinches or about one meter so that the cask 14 can be raised to the upperelevation at the cask preparation station 42. Dual eight inch doubleacting cylinders lift the cask 14 using non-flammable hydraulic fluid ata pressure of greater than 80% of the maximum operating pressure. Safetycatchers 76 are incorporated into the cylinders so that a failure of acylinder rod will nit be catastrophic. On loss of power, the cylinderscan be manually lowered to put the cask 14 in a safe condition. When thecask 14 is on the upender 26, it is captivated in several locations. Onthe bottom of the cask 14, an “L” shaped platform 84 is hydraulicallyoperated to latch the lower portion of the cask 14. This prevents thecask 14 from sliding and keeps the trunnions 56, 58 in their respectivepockets in the bed. A second hydraulic assembly latches the rear uppertrunnion 56 and prevents the cask 14 from tipping forward under even theworst anticipated seismic event. The locks fail safely in case of lossof power or loss of hydraulic fluid. On the bottom of the upendercarriage is an alignment or guide tool or assembly. This hydraulicallyactivated alignment assembly lowers onto the rails 40 that are embeddedin the floor of the fuel hall 34 to guide the cask transporter 16 inprecise alignment. This assembly is only a guide and does not havedriven wheels. A single hydraulic cylinder is used to raise (store) andlower (engage) the assembly.

At the first or cask prep station 42, the cask 14 is moved to thevertical position. The cask transporter 16 aligns the cask 14 with thehole 44 in the ceiling of the fuel hall 34 and the fuel building craneis used to perform cask component removal/replacement work. The cask 14is positioned so that the crane can take each lid out of the cask 14,bring it up through the hole 44 and place it on a rolling shelf.Operators can easily access the top of the cask 14 to remove bolts andprepare the cask for insertion of the fuel assemblies.

After the biological lid's bolts are removed, the cask 14 proceeds tothe second or biological lid station 46 to have the biological lidremoved and the seals inspected. Using the Hevi-Lift Hoist 48 or theequivalent mounted onto a bridge and trolley assembly, a grapple can bemaneuvered to attach to the biological lid and remove it from the cask14. The Hevi-Lift Hoist 48 is a 7.5 to 10 ton unit that has multiplesingle failure proof components in order that the lid cannot be droppedonto spent fuel. The hoist 48 has multiple brakes (CD brake, load brakeand regenerative braking) coupled with a duel rope system to ensure thatthe breakage of rope will not drop the load. The hoist 48 is operatedwith a variable frequency drive, such as a Smartorque drive, orequivalent for precise positioning. The bridge and trolley are veryshort spans providing approximately one foot (or about 0.3 meters) oftravel in the X and Y plane. The bridge and trolley are over sized toallow for a 10:1 design factor based on ultimate strength and areoperated using a standard starter and relay rather than VFD. The grappleis designed to meet the requirements of ASME N14.6-1993, “SpecialLifting Devices for Shipping Containers Weighing 10,000 pounds or More”and ASME BTH-1, “Design of Below the Hook Lifting Devices”. The grappleis designed to interface with the round lug on the top of the geologicalshield. The device has jaws that meet the standard configurationprofile. The jaws of the grapple pass through the opening (ID) in thecanister lifting lug and come to rest on the top of the lid. As theweight of the grapple shifts from being held by the hoist due to beingcarried by the lid, the linkage of the system of the grapple movesdownward and disengages the mechanical latch. The mechanical latch worksby using a T-shaped rod and cam profile that has the ability to move upand down, and to rotate. Similar to operating a ball point pen, the cammechanism in the latch alternates from extending and retracting theT-shaped rod. When the grapple travels downward, it activates the latchto move the wedge configuration to drive the jaws outward until fullstroke is obtained (approximately 2 inches). Once the grapple isattached to the lug, it is mechanically locked and cannot open as aresult of operator error. This is efficient because the mechanicalprinciple of wedges (incline planes) gives a mechanical advantage basedon the weight of the load lifted. The jaws cannot disengage whilelifting the load. When disengaging the cask, the reverse sequenceoccurs. On the downward motion of the grapple, the weight of the unitapplies a vertical force on a linage series which in turn applies ahorizontal force to retract the jaws. This all occurs simultaneouslyleaving the jaws retracted and the grapple in the unlatched position.The grapple can then be lifted free of the lid.

Once the biological lid has been removed, the cask transporter 16 movesthe cask 14 to the third or upper cask handling station 50 where thecask 14 is positioned against a penetration seal. As best shown in FIG.16, the upper cask handling station 18 includes a weldment 86 that hasfour hydraulic cylinders 88 that raise and lower the cask engagementtool 90. The cask engagement tool 90 includes the two pivoting paddles52 with the key slots 54 that fit over the upper trunnions 56 on theside of the cask 14. With the cask 14 aligned under the upper caskhandling station 18, the ten inch diameter cylinders 88 lower thepaddles 52, and an electro-mechanical actuator pivots the paddles 52down about their horizontal pivot axes and over the trunnions 56. Thecylinders 88 then rise slightly to ensure proper fit and take someinitial cask load. The cask 14 is disengaged from the cask transporter16, which backs away from the cask 14. With the entire cask 14 suspendedfrom the upper cask handling station 18, the cylinders 88 raise the cask14 into the penetration seal. The cylinders 88 rise together based on alinear encoder in each rod that feeds back to the control system toensure proper alignment. In addition to the linear encoders, the uppercask handling system 18 ensures proper alignment with guide tubes thatare positioned at each of the four corners. Gravity ensures the cask 14hangs straight down since the round trunnions 56 seated in the round keyslots 54. As the cask 14 is raised, it interfaces with a stainless steelpenetration lower flange that has a multi-level seal system. Once thecask 14 is seated, the seals are filled with air to seal the interfacebetween the penetration lower flange and the cask 14 so that there is noleakage even with the pressure resulting from a significant watercolumn. In between the seals are leak detection sensors that provideassurance that the main and backup seals are tight. With the cask 14properly seated, tapered shear pins are inserted between the stationarystructure and the lift frame 18 to lock the cask 14 in place. Thisprovides assurance that even during a seismic event, the cask 14 willnot become disengaged from the penetration seal.

Once the cask 14 has been raised and seated on the penetration seal, thelower seismic restraint 22 engages the lower trunnions 58 of the cask 14to securely hold the assembly. This carbon steel weldment 92 is mountedpermanently to the floor in the fuel hall 34 below the penetration 32.As best shown in FIG. 17, the seismic restraint 22 includes twohorizontally moving arms 94 that extend out at the height of thetrunnions 58. The cask transporter 16 straddles the lower seismicrestraint 22 when it delivers the cask 14. After the cask transporter 16has released the cask 14 and backed out of the way, the restraint 22actuates to engage the trunnions 58 using an ACME screw to bring thearms 94 over the trunnions 58. A separate locking plate operated by amechanical-electrical actuator locks both arms to the cask 14 so theunit can handle seismic forces in all three planes. Once the cask 14 isfilled with fuel assemblies, the lower seismic restraint 22 releases thecask 14 by shifting locks and retracting the arms 94 from the cask 14.The cask 14 can then be lowered onto the cask transporter 16 and theloaded cask 14 can be removed from the fuel hall 34.

As best shown in FIGS. 18 to 20, the penetration upper hatch or cover 20includes a rim 96, a cover 98 with latches 100, o-rings 102, latchcylinders 104, a hatch cylinder 106, a hydraulic power unit 108, piping110, and leak sensors 112. The rim 96 is a stainless steel weldmentsized to fit the hole at the upper penetration 32. It houses the o-ringseals 102, provides a base for installation of the hatch cylinder 106and the latch cylinders 104, and offers a pivot for the cover 98. Thecover 98 is a stainless steel weldment. It mates with the rim 96 at thepivot points, through the hatch cylinder 106, through the latchcylinders 104, and at the o-ring seals 102 where it provides sealing.The o-rings 102 are fabricated o-rings of about a 1.0 inch crosssection. The o-rings 102 are fabricated to three different diameters toprovide three concentric sealing surfaces. Material is compatible withthe water of the spent fuel building and a high radiation application.The latch cylinders 104 are stainless steel water hydraulic cylinders of3.25 inch bore and 3.5 inch active stroke. They are front flange mountedand rear flange retrained to decrease deflection when operating. The rodis 2.0 inches in diameter with a ¾×15 degree end taper. This taperforces the cover tight against the o-ring seals providing a positiveseal. The hatch cylinder 106 is a stainless steel water hydrauliccylinder of 4.0 inch bore, 16.0 inch active stroke, and 1.5 inchdiameter rod. It is mounted to the rim 96 at its base end and to thecover 98 at its rod end providing the force to open and close the cover98. The hydraulic power unit (HPU) 108 is a motor driven water hydraulicpump which provides flow and pressure to operate the cylinders 104, 106.It incorporates water hydraulic valves to operate the latch cylinders104 or the hatch cylinder 106. Piping 110 to the cylinders 104, 106 isstainless steel tubing fabricated to the dimensions of the SFBtransferring flow and pressure from the HPU 108 to the cylinders 104,106. The leak sensors 112 are switches which provide a signal to thesystem when sensing a leak through the o-rings 102.

Operation of the penetration upper hatch cover 20 begins with the cover98 closed and locked. When it is desired to open the cover 98, theoperator activates the valve operating the latch cylinders 104. Thesecylinders 104 retract, pulling their rods (pins) from the cover latches100. Sensors confirm when the cover is unlatched. The operator thenactivates the hatch cylinder 106. This cylinder 106 pulls on the coverlever and opens the cover 98. The cover rotates from zero degreesthrough about 105 degrees at full open. Sensors confirm that the coveris fully open and the penetration 20 is ready for passage of the fuelassemblies. Fuel is passed through the penetration 20 until the spentfuel cask 14 is full, and must be removed. To close the penetration 20,the operator activates the hatch cylinder 106 to close the cover 98. Thecylinder 106 moves the lid 98 until the CG is past center and thenrestrains the lid 98 as it lowers down onto the o-ring seals 102 of therim 96. A hatch cylinder pin may be manually pulled to allow the cover98 to close in an emergency. The illustrated embodiment has threeo-rings 102 arranged circumferentially about the hatch opening. Theseo-rings 102 seal on their tops and bottoms against the cover 98 and therim 96. The operator activates the latch cylinders 104 which drive theirtapered rods (pins) into the latches 100 of the cover 98. This taperfurther forces the lid 98 tight against the o-rings 102 ensuring theircomplete seal. Sensors indicate when the latches 100 are fully engaged.Since there is no residual force attempting to release the latchcylinders 104, the lid 98 will remain closed and sealed during anyunforeseen conditions. Hand pumps can release the latches 100 duringemergency situations.

FIG. 21 illustrates piping of the cask handling room 50. The pipingsystem includes valves for filling the cask 14 including venting, valvesto spray down the annulus and cask 14 with de-mineralized water, and apressure gauge and level indicator for the cask 14. Double valves areprovided so that a failed unit can be isolated. Most of the valves aremanual and located outside the fuel hall 34. Those valves and gaugesinside the fuel hall 34 that are not accessible when personnel are notallowed in the vicinity are electrically operated.

FIG. 22 is an electrical schematic of the control system of the caskhandling system 12. The cask handling system control is housed in afloor mounted NEMA 12 enclosure/main control console. The enclosure/maincontrol console contains two PLCs, an operator interface and all videocamera controls with LED flat screen monitors. The control systememploys two independent PLCs. The first PLC is an Allan BradleyControLogix PLC or the equivalent and is dedicated to the control andoperation of the cask handling system 12. The second PLC is an AlanBradley dual processor GuardLogic PLC or the equivalent and is used formonitoring all safety related devices and functions. This PLC, when usedwith safety I/O blocks is safety certified SIL-3 per IEC 61508. Both PLCprocessors will communicate over an Ethernet/IP network. The operatorinterface consists of an Allan Bradley Panelview Plus LED touch screenmonitor or the equivalent that is in direct communication with theoperational PLC over an Ethernet/IP network. This interface isprogrammed with various operator control screens as well as screens foroperational interlocks, fault messages, and troubleshooting aids. Allmotion is interlocked in the PLC program to assure all operations areperformed in the proper sequence. A hard wired safety emergency stoppushbutton is located at each of the three working stations as well asat the remote main control console. When any of the emergency stopbuttons are pressed, all motion relating to the cask handling systemwill stop. The camera system will consist of several strategicallyplaced video cameras for monitoring various cask loading operations andoverall cask handling status. Where necessary, cameras will be radiationhardened and incorporate a pan/tilt/zoom feature. Camera joystickcontrols along with the associated flat panel color viewing monitors arelocated at the remote man control console. Once inside the fuel hall,the cask transporter is powered via a plugged in power cable and controland control of the cask transporter will be accomplished by means of acontrol chief radio remote control box. In addition, the main controlconsole PLC will monitor various functions of the on board casktransporter PLC over a connected network communication cable.

It is apparent from the above disclosure that the improved cask handlingsystem 12 utilizes a number of innovations to reduce the time to performthe task and significantly reduces the number of components. The sealingprocess where the cask 12 is interfaced to the spent fuel pool issimplified to allow gravity to help align the system to prevent anyleakage. The self-powered mobile cask handling vehicle 16 handles thecask 14 at a number of stations and transports the casks 14 throughoutthe site.

From the foregoing disclosure and detailed description of certainpreferred embodiments, it will be apparent that various modifications,additions and other alternative embodiments are possible withoutdeparting from the true scope and spirit of the present invention. Theembodiments discussed were chosen and described to provide the bestillustration of the principles of the present invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the presentinvention as determined by the appended claims when interpreted inaccordance with the benefit to which they are fairly, legally, andequitably entitled.

What is claimed is:
 1. A method for removing spent nuclear fuel from afuel pool comprising the steps of: moving a cask below a handlingmechanism that is at a fixed position below a penetration of the fuelpool using a transporter while a cover of the penetration is closed;raising the cask off of the transporter using the handling mechanism;securing the cask to the penetration while the cask is supported by thehandling mechanism; moving the transporter away from the cask and thehandling mechanism after the cask is raised off of the transporter bythe handling mechanism; while the cask is sealed to the penetration,opening the cover of the penetration; inserting the spent fuel into thecask; after the spent fuel is inserted into the cask, unsealing the caskfrom the penetration; moving the transporter back below the cask and thehandling mechanism and lowering the cask loaded with the spent fuel ontothe transporter using the handling mechanism; and moving the transporterwith the cask loaded with the spent fuel away from the penetration andthe handling mechanism.
 2. The method according to claim 1, wherein thestep of raising the cask from the transporter includes the steps ofengaging upper trunnions of the cask with pivoting paddles of thehandling mechanism.
 3. The method according to claim 2, wherein thepivoting paddles have key-holes receiving the upper trunnions.
 4. Themethod according to claim 1, wherein the handling mechanism comprises: afixed position frame configured to permit the transporter to movethereunder while supporting the cask; a cask engagement tool movable inthe vertical direction relative to the frame and configured toselectively move the spent nuclear fuel cask in the vertical directionrelative to the frame when the cask is secured to the cask engagementtool to selectively raise and lower the cask onto and off of thetransporter; a plurality of hydraulic cylinders extending between theframe and the cask engagement tool and configured to move together forraising and lowering the cask engagement tool relative to the frame; anda pair of paddles carried by the cask engagement tool and pivotablyattached to the cask engagement tool for selectively engaging uppertrunnions of the cask; and an actuator for selectively pivoting the pairof paddles into and out of engagement with the upper trunnions of thecask.
 5. The method according to claim 4, wherein the paddles havekeyholes for receiving the upper trunnions.
 6. The method according toclaim 4, wherein the frame is secured below a penetration of a fuelpool.
 7. The method according to claim 4, wherein the frame is securedbelow the penetration of the fuel pool.
 8. The method according to claim4, wherein the cask engagement tool linearly moves in the verticaldirection relative to the frame.
 9. The method according to claim 4,wherein the linear actuators linearly raise and lower the caskengagement tool relative to the frame.
 10. The method according to claim4, wherein the handling mechanism is configured to engage only uppertrunnions of the cask.
 11. The method according to claim 1, wherein thetransporter is self-powered vehicle.
 12. The method according to claim11, wherein the transporter is guided by rails near the penetration. 13.The method according to claim 11, wherein the self-powered vehiclecomprises a body; an upender secured to the body for holding the caskand moving the cask between vertical and horizontal orientations; aplurality of independently driven and independently steered duel wheelsets on each lateral side of the body; a plurality of drive motors fordriving the plurality of duel wheel sets; a plurality of rotaryactuators for steering the plurality of duel wheel sets; and adiesel-engine driven electric generator carried by the body forproducing electric power to selectively move the upender structure, toselectively drive each of the duel wheel sets, and to selectively steereach of the duel wheel sets.
 14. The vehicle according to claim 13,wherein each of the duel wheel sets includes a pair of coaxial wheels,one of the plurality of drive motors is located between the pair ofwheels and coaxial with the pair of wheels, one of the plurality ofrotary actuators is located above the drive motor and having a verticalaxis of rotation for selectively rotating the pair of wheels, and thedrive motor located between the pair of wheels;
 15. The method accordingto claim 13, wherein the plurality of drive motors is a plurality ofhydraulic motors.
 16. The method according to claim 13, wherein theplurality of rotary actuators is a plurality of rack and pinionactuators.
 17. The method according to claim 13, wherein the pluralityof duel wheel sets includes four duel wheel sets on each lateral side ofthe body.
 18. The method according to claim 1, further comprising thestep of filling the cask with water while the cask is supported by thehandling mechanism to equalize pressure with water within the fuel poolprior to the step of opening the penetration cover.
 19. The methodaccording to claim 1, after the step of moving the transporter away fromthe cask and the handling mechanism after the cask is raised off of thetransporter by the handling mechanism, further comprising the step ofengaging lower trunnions of the cask with a keyed structure of a seismicrestraint to prevent swinging motion of the cask in a seismic event.